Strange RadioButton group behavior with ToolBar

RadioButton‘s grouping implementation doesn‘t take into the consideration the scenario in which those RadioButtons belonging to the same group might reside in different visual tree. This is true when used inside ToolBar, because those content displayed in the over-flow section of ToolBar are actually residing in a Popup, the following code shows a possible workaround:

 



Code Block
using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;

namespace Sheva.Windows.Controls
{
    public class WorkaroundToolBar : ToolBar
    {
        protected override void PrepareContainerForItemOverride(DependencyObject element, Object item)
        {
            base.PrepareContainerForItemOverride(element, item);
            WorkaroundRadioButton radioButton = element as WorkaroundRadioButton;
            if (radioButton != null)
            {
                radioButton.SetValue(DefaultStyleKeyProperty, ToolBar.RadioButtonStyleKey);
            }
        }
    }

    public class WorkaroundRadioButton : RadioButton
    {
        protected override void OnChecked(RoutedEventArgs e)
        {
            Boolean bypassBuildinUncheckLogic = false;
            DependencyObject parent = base.Parent;
            if (parent != null)
            {
                foreach (DependencyObject logicalChild in LogicalTreeHelper.GetChildren(parent))
                {
                    // If there is any logical child connected to the popup, we should employ our own invention to uncheck the group.
                    if (GetPopupFromVisualChild(logicalChild as Visual) != null)
                    {
                        bypassBuildinUncheckLogic = true;
                    }
                }

                if (bypassBuildinUncheckLogic)
                {
                    foreach (DependencyObject logicalChild in LogicalTreeHelper.GetChildren(parent))
                    {
                        WorkaroundRadioButton radioButton = logicalChild as WorkaroundRadioButton;
                        if (radioButton != this && !String.IsNullOrEmpty(radioButton.GroupName) && radioButton.GroupName == base.GroupName)
                        {
                            radioButton.IsChecked = false;
                        }
                    }
                }
            }

            if (!bypassBuildinUncheckLogic)
            {
                base.OnChecked(e);
            }
        }

        private static Popup GetPopupFromVisualChild(Visual child)
        {
            Visual parent = child;
            FrameworkElement visualRoot = null;
            while (parent != null)
            {
                visualRoot = parent as FrameworkElement;
                parent = VisualTreeHelper.GetParent(parent) as Visual;
            }

            Popup popup = null;
            if (visualRoot != null)
            {
                popup = visualRoot.Parent as Popup;
            }

            return popup;
        }
    }
}
<Window x:Class="AnswerHarness.ToolBarGroupNameProblem"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cc="clr-namespace:Sheva.Windows.Controls"
    Title="ToolBarGroupNameProblem" Height="300" Width="300">
  <DockPanel>
    <cc:WorkaroundToolBar Height="30" VerticalAlignment="Top" DockPanel.Dock="Top">
      <cc:WorkaroundRadioButton GroupName="Group1" Content="Radio1" x:Name="Radio1"/>
      <cc:WorkaroundRadioButton GroupName="Group1" Content="Radio2" x:Name="Radio2"/>
      <cc:WorkaroundRadioButton GroupName="Group1" Content="Radio3" x:Name="Radio3"/>
      <cc:WorkaroundRadioButton GroupName="Group1" Content="Radio4" x:Name="Radio4"/>
    </cc:WorkaroundToolBar>
    <Button Width="120" Height="30" Name="btn"/>
  </DockPanel>
</Window>